The present invention relates to a dehumidifying air-conditioning apparatus and a dehumidifying air-conditioning system, and more particularly to a dehumidifying air-conditioning apparatus having a desiccant, and a dehumidifying air-conditioning system having such a dehumidifying air-conditioning apparatus.
Heretofore, there has been used a desiccant air-conditioning apparatus which utilizes a low temperature heat source and a high temperature heat source, as shown in FIG. 16. The air-conditioning apparatus has a path for process air A from which moisture is adsorbed by a desiccant wheel 103, and a path for regeneration air B which is heated by the high temperature heat source and then passed through the desiccant wheel 103 that has adsorbed the moisture to desorb the moisture in the desiccant for regenerating the desiccant. In order to heat the regeneration air with the high temperature heat source, a heating medium is supplied to a heat exchanger 120 via a path 151 connected to a high temperature heat source supply port 42, and returned to a high temperature heat source return port 43 via a path 152.
The air-conditioning apparatus shown in FIG. 16 comprises a sensible heat exchanger 104 for exchanging heat between the process air from which moisture is adsorbed and the regeneration air before it regenerates a desiccant in the desiccant wheel 103 and before it is heated by the heat exchanger 120. The regeneration air is heated to a certain extent by the sensible heat exchanger 104 before being heated by the heat exchanger 120, and the process air that has been dried by the desiccant is cooled to a certain extent by the sensible heat exchanger 104. Thereafter, the process air is further cooled by a low temperature heat source which is supplied to a heat exchanger 115 from a low temperature heat source supply port 40 via a path 161 and discharged to a low temperature heat source return port 41 via a path 162. In the conventional example shown in FIG. 16, the process air that has been discharged from the heat exchanger 115 is humidified by a humidifier 106, and supplied, with an increased humidity and a lowered dry-bulb temperature, to an air-conditioned space 101.
With this air-conditioning apparatus, the sensible heat exchanger 104 for exchanging heat between the process air that has been discharged from the desiccant wheel 103 and the regeneration air that is to be supplied to the heat exchanger 120 increases an energy-saving effect. The high temperature heat source and the low temperature heat source of the conventional air-conditioning apparatus shown in FIG. 16 are provided by a compression heat pump (not shown).
FIG. 17 shows a Mollier diagram of the compression heat pump used in the conventional air-conditioning apparatus shown in FIG. 16. This diagram is a Mollier diagram in the case where HFC134a is used as the refrigerant. A point a represents a state of the refrigerant evaporated by an evaporator of the heat pump, and the refrigerant is in the form of a saturated gas. The refrigerant has a pressure of 4.2 kg/cm2, a temperature of 10xc2x0 C., and an enthalpy of 148.83 kcal/kg. A point b represents a state of the gas drawn and compressed by a compressor of the heat pump, i.e., a state at the outlet port of the compressor. In this state, the refrigerant has a pressure of 24.1 kg/cm2 and a temperature of 85xc2x0 C., and is in the form of a superheated gas. The refrigerant gas is cooled by a heating medium in a condenser of the heat pump (heats the heating medium), and reaches a state represented by a point c in the Mollier diagram. In the point c, the refrigerant is in the form of a saturated gas and has a pressure of 24.1 kg/cm2 and a temperature of 75xc2x0 C. Under this pressure, heat is removed from the refrigerant by the heating medium, and the refrigerant is condensed and reaches a state represented by a point d. In the point d, the refrigerant is in the form of a saturated liquid and has the same pressure and temperature as those in the point c, i.e., a pressure of 24.1 kg/cm2 and a temperature of 75xc2x0 C. and an enthalpy of 127.13 kcal/kg. The refrigerant liquid is depressurized by an expansion valve to a saturation pressure of 4.2 kg/cm2 at a temperature of 10xc2x0 C. A mixture of the refrigerant liquid and the gas at a temperature of 10xc2x0 C. is delivered to the evaporator, in which the mixture removes heat from a chilling medium and is evaporated to reach the saturated gas at the point a in the Mollier diagram. The saturated gas is drawn into the compressor again, and the above cycle is repeated. FIG. 18 shows the manner in which the temperature changes in the heat exchange between the refrigerant and the heating medium.
The cooled chilling medium is supplied via the path 161 to the heat exchanger 115, and returned via the path 162 to the evaporator of the heat pump. The heating medium that has been heated to about 70xc2x0 C. is supplied via the path 151 to the heat exchanger 120, in which the heating medium is cooled to 60-65xc2x0 C., and then returned via the path 152 to the condenser of the heat pump. The sensible heat exchanger 104 comprises a rotary heat exchanger as shown in FIG. 16, or a cross-flow type heat exchanger in which a process air and a regeneration air flow perpendicularly to each other.
In the above conventional air-conditioning apparatus, the sensible heat exchanger 104 for preliminarily cooling the process air before it is cooled by the heat exchanger 115 plays an important role. However, since the sensible heat exchanger 104 generally occupies a large volume in the system, it is difficult to design the system, and the system is forced to be large in size. Further, since a large amount of the heating medium and the chilling medium is used in the system, the diameter of heating medium pipes through which the heating medium circulates becomes large. Therefore, it is difficult to install those heating medium pipes. Furthermore, a pump for delivering the heating medium tends to consume large power.
It is therefore an object of the present invention to provide a compact dehumidifying air-conditioning apparatus, and a dehumidifying air-conditioning apparatus and a dehumidifying air-conditioning system with reduced power consumed for delivering a heating medium or a chilling medium.
To achieve the above object, a dehumidifying air-conditioning apparatus according to the present invention described in claim 1 has, as shown in FIG. 1, a moisture adsorption device 103 having a desiccant for adsorbing moisture from process air, adsorbed moisture being desorbed by regeneration air; a first heat exchanger 120 for exchanging heat between the regeneration air and a heating medium, the first heat exchanger 120 being disposed upstream of the moisture adsorption device 103 with respect to a flow of the regeneration air; a second heat exchanger 220 for exchanging heat between the process air and the heating medium, the second heat exchanger 220 being disposed downstream of the moisture adsorption device 103 with respect to a flow of the process air; and a heating medium supply device HP for heating the heating medium supplied to the first heat exchanger 120 and the second heat exchanger 220; wherein the arrangement is such that the heating medium supplied from the heating medium supply device HP flows through the first heat exchanger 120 and the second heat exchanger 220 in the order named.
With the above arrangement, since the heating medium supplied from the heating medium supply device HP flows through the first heat exchanger and the second heat exchanger in the order named, heat equivalent to a portion of heat used to heat the regeneration air in the first heat exchanger can be recovered from the process air in the second heat exchanger.
As described in claim 2, the dehumidifying air-conditioning apparatus may further comprise a third heat exchanger 115 for exchanging heat between the process air and a chilling medium, and the third heat exchanger 115 may be disposed downstream of the second heat exchanger 220 with respect to the flow of the process air. With the third heat exchanger 115, it is possible to further cool the process air.
As described in claim 3, in the dehumidifying air-conditioning apparatus described in claim 2, the heating medium supply device HP may be arranged to supply the chilling medium, and comprise a heat pump for pumping heat from the chilling medium to the heating medium. With this arrangement, since the heat pump pumps heat from the chilling medium to the heating medium, the heat can effectively be utilized.
As described in claim 4, in the dehumidifying air-conditioning apparatus described in claim 2 or 3, the difference between the temperature of the chilling medium at an inlet of the third heat exchanger 115 and the temperature of the chilling medium at an outlet of the third heat exchanger 115 is 10xc2x0 C. or less. With this arrangement, heat can be recovered from another sensible heat processing machine (e.g., a fan coil) installed in an air-conditioned space at an air temperature ranging from 25 to 27xc2x0 C. via cold water (20 to 10xc2x0 C.), and can be reused to heat the heating medium. Therefore, the heat can be used in multiple ways, and an energy-saving system can be achieved.
As described in claim 5, in the dehumidifying air-conditioning apparatus described in any one of claims 1 through 4, the difference between the temperature of the heating medium at an inlet of the first heat exchanger and the temperature of the heating medium at an outlet of the second heat exchanger should preferably be 15xc2x0 C. or more.
With the above arrangement, the temperature difference of the heating medium that can be used is a large value of 15xc2x0 C. or more. Therefore, in a system in which a pipe for the heating medium is long and which uses a heating medium delivery device (a pump or the like), the power to deliver the heating medium is reduced, and the diameter of a pipe for delivering the heating medium is reduced. The pipe can thus be installed with ease at a reduced cost.
To achieve the above object, a dehumidifying air-conditioning system according to the present invention described in claim 6 has, as shown in FIG. 14, a dehumidifying air-conditioning apparatus 70A through 70E according to any one of claims 1 through 5; a heating medium pipe 30, 31 for supplying the heating medium from the heating medium supply device 1 to the first heat exchanger 120 and the second heat exchanger 220; and a chilling medium pipe 20, 21 for supplying the chilling medium from the heating medium supply device 1 (HP) to the third heat exchanger 115.
An invention according to another aspect is described in claim 7. As shown in FIG. 1, a dehumidifying air-conditioning apparatus comprises a moisture adsorption device 103 having a desiccant for adsorbing moisture from process air, adsorbed moisture being desorbed by regeneration air; a first heat exchanger 120 for exchanging heat between the regeneration air and a heating medium in a vapor phase, the first heat exchanger being disposed upstream of the moisture adsorption device with respect to a flow of the regeneration air; and a second heat exchanger 220 for exchanging heat between the process air and the heating medium which has exchanged heat in the first heat exchanger 120, the second heat exchanger being disposed downstream of the moisture adsorption device 103 with respect to a flow of the process air. Typically, the heating medium which has exchanged heat in the first heat exchanger 120 is condensed into a liquid phase, and the second heat exchanger 220 exchanges heat between the heating medium in the liquid phase and the process air.
With the above arrangement, inasmuch as the heating medium flows through the first heat exchanger and the second heat exchanger in the order named, heat equivalent to a portion of heat used to heat the regeneration air in the first heat exchanger can be recovered from the process air by the second heat exchanger. Typically, the heat is transferred using phase changes of the heating medium.
As described in claim 8, the above apparatus may further comprise a third heat exchanger 115 for exchanging heat between the process air and a chilling medium in a liquid phase, and the third heat exchanger may be disposed downstream of the second heat exchanger 220 with respect to the flow of the process air. With this arrangement, the third heat exchanger 115 further cools the process air that has been cooled by the second heat exchanger 220.
As described in claim 9, the dehumidifying air-conditioning apparatus described in claim 7 or 8 may further comprise a switching device 172 disposed between the first heat exchanger 120 and the second heat exchanger 220 for changing a flow of the heating medium which has exchanged heat in the first heat exchanger 120. With this arrangement, the switching device changes the flow of the heating medium, so that the heating medium can bypass the second heat exchanger 220.
To achieve the above object, a dehumidifying air-conditioning system according to the present invention defined in claim 10 may comprise, as shown in FIG. 15, a dehumidifying air-conditioning apparatus described in claim 8; and a heat pump 1 for pumping heat from the chilling medium supplied to the third heat exchanger 115 to the heating medium supplied to the first heat exchanger 120.
With this arrangement, the heat pump can pump the heat removed from the chilling medium in the third heat exchanger, and the pumped heat can be imparted to the heating medium in the first heat exchanger. The heat is transferred using phase changes of the heating medium. Typically, the heating medium can spontaneously be circulated by gravity, so that the power to transfer the heat can extremely be reduced.
As described in claim 11, the dehumidifying air-conditioning system according to claim 10 may comprise a plurality of the dehumidifying air-conditioning apparatus for one the heat pump. With this arrangement, it is possible to construct a system in which the chilling medium that is heated and cooled in a centralized manner by the single heat pump is used by a plurality of dehumidifying air-conditioning apparatus.
As described in claim 12, in the dehumidifying air-conditioning system according to claim 10 or 11, the heat pump 1 may comprise a fourth heat exchanger 35 for imparting heat to the heating medium; and a fifth heat exchanger 25 for removing heat from the chilling medium.
As described in claim 13, in the dehumidifying air-conditioning system described in claim 12, the fourth heat exchanger 35 should preferably be disposed relatively vertically downwardly of the dehumidifying air-conditioning apparatus, and the fifth heat exchanger 25 should preferably be disposed relatively vertically upwardly of the dehumidifying air-conditioning apparatus.
With the above arrangement, typically, heat is imparted to the heating medium to evaporate the heating medium in the fourth heat exchanger. Since the evaporated heating medium is lighter than the heating medium as a liquid, the evaporated heating medium is spontaneously circulated to the dehumidifying air-conditioning apparatus positioned relatively vertically upwardly of the fourth heat exchanger. Typically, heat is removed from the chilling medium to liquefy the chilling medium in the fifth heat exchanger. Since the liquefied chilling medium is heavier than the chilling medium as a gas, the liquefied chilling medium is spontaneously circulated to the dehumidifying air-conditioning apparatus positioned relatively vertically downwardly of the fifth heat exchanger.
As described in claim 14, the dehumidifying air-conditioning system according to any one of claims 10 through 13 may further comprise a chilling machine 9 for removing heat from the chilling medium. When a cooling load is large, the chilling machine 9 can be operated in addition to the heat pump 1 to process the large cooling load. In this case, the chilling machine may be positioned anywhere in the path of the chilling medium. Typically, the chilling machine may be connected to the fifth heat exchanger 25, and may have an evaporator incorporated in the fifth heat exchanger 25, for example.